1. Field of the Invention
The invention concerns a process for the manufacture of odorants, and novel nitriles used therein.
2. Background Art
The expensive, optically active odorant (-)-(3aR-(3a.alpha.,5a.beta.,9a.alpha.,9b.beta.))-dodecahydro-3a,6,6,9a-te tramethyl-naphtho[2,1-b]furan, is commercially available under various trade names, namely AMBROX.RTM. (Firmenich), AMBROXAN.RTM. (Henkel), AMBERLYN.RTM. (Quest), SYLVAMBER.RTM. (BASF) and AMBROXID.RTM. (Haarman & Reimer). Several processes for the manufacture of (-)-(3aR-(3a.alpha.,5a.beta.,9a.alpha.,9b.beta.))-dodecahydro-3a,6,6,9a-te tramethyl-naphtho[2,1-b]furan are known. These processes all start with sclareolid, i.e., (3aR-(3a.alpha.,5a.beta.,9a.alpha.,9b.beta.))-decahydro-3a,6,6,9a-tetramet hylnaphtho[2,1-b]furan-2(1H)-one. Sclareolid itself is obtained by oxidation of sclareol (muscatel sage oil) by way of an oxidizing agent such as chromic acid. Sclareol in turn is obtained from the natural source Salvia sclarea by extraction. At present, however, the amount of commercially available sclareol is limited and the price can fluctuate enormously depending on the harvest of Salvia sclarea. A further disadvantage of this process is use of chromic acid in the oxidation step which is problematic from the point of view of environmental protection. There accordingly exists a need for an industrially realizable process for the manufacture of dodecahydro-3a,6,6,9a-tetramethylnaphtho[2,1-]furan, which does not use sclareol and, accordingly is not dependant on the availability of sclareol and, moreover, which is more economical and more environmentally friendly than the process hitherto used. This is now possible by means of the process in accordance with the invention.